stemco, a division of senasys

1/2″ Manual Reset Snap Disc Thermostats

The 432 Series is our 1/2″ Manual Reset Snap Disc Thermostats. The 1/2″ manual reset snap disc thermostats are ideally suited for applications where you want to call special attention to a specific temperature malfunction. The 432 series can be used as a safety limit that will break on temperature rise. The thermostat must be manually reset once tripped requiring a human to intervene once tripped.

Custom options

Designed & manufactured to meet requirements of original equipment manufacturers worldwide.

high quality

Senasys products are 100% tested before they leave our facilities.


Senasys products are UL/cUL Recognized.

made in u.s.a.

Senasys products are designed & manufactured in Eau Claire, Wisconsin, U.S.A.

The 432 Series is our 1/2″ manual reset snap disc. This series is ideally suited for applications where you want to call special attention to a specific temperature malfunction. The 432 series can be used as a safety limit that will break on temperature rise. Our manual reset thermostat switches are ideal when you want to call special attention to a temperature malfunction. Because the switch needs to be manually reset, a human must interact with the switch and solve the problem before the equipment or appliance can work again.

The 432 thermostats use a bimetal disc for snap action, providing positive and instantaneous opening of the electric circuit. The 432 series can be used as a safety limit that will break on temperature rise. Once tripped, the thermostat can be reset once the temperature has dropped a minimum of 25°F. The reset differential will increase as the specified break temperature increases.

Product Specifications

  • 1/2″ Bi-Metal Snap Action Disc
  • Manual Reset
  • Breaks on temperature rise
  • Single-pole, Single-throw (SPST)
  • 15 Amps @ 120VAC; 10 Amps @ 240VAC, 6,000+ cycles
  • 100°F to 350°F (40°C to 175°C) Temperature Range
  • Bi-Metal is available enclosed, or exposed for a faster reaction
  • Small Footprint
  • Variety of mounting options, such as pipe and stud mounts.
  • Variety of terminal configurations available.
  • UL Listed
  • Made in U.S.A.

For a more economical solution, Senasys has built relationships with overseas suppliers to provide our customers thermostats at a lower cost, with the same high quality as our snap disc thermostats built in the U.S.A. Additionally, this has allowed us to expand our catalog offering to meet other application requirements, including:

  • Ratings up to 25A@277VAC
  • -20°F to 480°F (-30°C to 250°C) Temperature Range
  • cUL & TUV Listed

Contact us for more information.

Mounting Options

With snap discs, different applications will require a different snap disc mounting style. Temperature switches can be installed in a variety of environments, and the right mounting bracket is needed to make sure that the switch is able to perform accurately. Even if a switch functions at the right temperature, the wrong bracket can cause it switch at the wrong time or even not switch at all. See a variety of available mounting options below, or click here to learn more.

If you need a style that isn’t shown here, contact us! We offer custom bracket options as well.

Select from a variety of mounting options, including pipe and stud mounts.

Direct Mount
Surface Mount
Large Surface Mount
Airstream (Extended Cup) Mount
Large Airstream (Extended Cup) Mount
Loose Hold Bracket
Threaded Stud Mount
NPT Stud Mount
Pipe Mount

Terminal Options

Our 432 series is available with a variety of terminal options. Our standard terminals are 1/4″ Quick Connect Terminals.

A variety of terminal bends & orientations are also available. Our standard terminal bends are 0°, 45° or 90°.

Learn more about our terminal options available  here.

For other custom options, please  contact us.

1/4″ Quick Connect
3/16″ Quick Connect
Solder Terminals
Flat Eyelet
Offset Eyelet
Long Strap
Barrel Solder
Wire Crimp

Standard Temperature Options

Below is a list of our common, off the shelf, bi-metal temperature options. Custom temperature options available. Please contact us.

Disc Number


Open: 125°F ±5°F Close: Manual


Open: 160°F ±8°F Close: Manual


Open: 200°F ±6°F, Close: Manual


Open: 220°F ± 5°F Close: Manual


Open: 275°F ±10°F Close: Manual

Common Applications

Our 432 series 1/2″ manual reset snap disc thermostats are found in a variety of applications. Choose a category below to learn more.

Frequently Asked Questions


What is a bi-metal snap disc?

Our snap disc thermostats are created with bimetal discs in them that react to temperature changes (rise or fall) and ‘snap’ causing the circuit to open or close. We form our discs from one of three bimetal compositions. Click here to learn more.

How are snap disc thermostats tested?

Senasys tests our snap disc thermostats through air, fluid, hot plate and other testing standards. Learn more about our quality inspection here.

What is a manual reset temperature switch?

A snap disc temperature switch that opens (limit) when temperature rises in a system.

How do you reset the temperature switch?

It’s simple. Press the red button!

When are manual reset switches commonly used?

These temperature switches are used when the switch should NOT reset once the system has shut down and returned to ambient temperature. Someone needs to interfere with the system before safely operating again.

What custom temperatures are available?

For small quantities, we can build anything from 0°F to 350°F. Contact us for higher temperatures.

When should an exposed snap disc cap be used?

One of the standout characteristics of an exposed cap is its’ use of a black exposed disc. This disc serves as a crucial element in sensing temperature fluctuations swiftly, enabling the switch to respond rapidly to environmental changes. This quick thermal response is especially important in applications where precise temperature control is paramount, such as in thermostats, industrial control systems, and appliances. The exposed caps are available for all non-epoxied snap disc thermostats within the Senasys catalog. 

For more information on exposed snap disc caps, click  here

When should gold contacts be used in place of silver?

One of the key advantages of gold contacts is their significantly lower contact resistance when compared to high-current silver contacts. This low resistance translates into improved electrical conductivity, allowing for smoother and more reliable signal transmission. This is especially important in applications where even the slightest interruption or distortion in the signal could lead to critical errors or malfunctions.

For more information on when gold contacts should be used, click here.

How much power does a snap disc thermostat use?

A snap disc thermostat does not use any power. Instead it acts as a circuit breaker for a system.

What material are snap disc thermostats made from?

The body of the switch is plastic, and the mounting cap is either steel, aluminum, or brass.

What is the differential of a snap disc thermostat?

For these types of switches 10ºF is about the smallest range they can maintain cost effectively and consistently.

For complex systems actual testing is usually pretty important. We support this process by making it easy to test multiple package styles and disc temps in sequence or all at once just give us a call. Learn more about temperature differentials here.

What is the temperature tolerance of my snap disc thermostat?

Our standard tolerance is between 5°F to 10°F, but tighter tolerance options are available. We also offer a min/max type. Click here to learn more, or contact us with your requirements.

Where should I locate my thermostat when installing into my equipment?

The location of the temperature switch inside your heating element should be well thought through. Temperature will change in various locations within the system depending on the heating element location. The further you distance from the heating element, the lower the temperature. Where a temperature switch is located will determine how accurate it can measure and control the system. Senasys typically recommends with all of our temperature switches the closer you can get to the heating element the better for the most accurate reading and fastest response time.

Cross Reference

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432 Series




OM/OMH Series

1/2″ Bi-Metal Snap Disc
Manual Reset

Breaks on Temp. Rise

100°F to 350°F Temperature Range
15 Amps @ 120VAC

6,000 cycles

Single Pole, Single Throw


Surface, Pipe & Stud Mount Options
Variety of Terminal Options
UL Listed
Made in U.S.A.

Build A Thermostat

Follow the below nomenclature guide to determine the 432 series manual reset thermostat to meet your application requirements.

Other custom options such as bracket, pipe mount, terminals and more available.  Contact  our technical support team with your application requirements for quote.

430 or 432 Snap Disc Thermostat Nomenclature

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